Can I add more parameter in the equation of a solar cell Model for reverse avalnche break down

Hello ,

Simulink proveds a model for solar cell and it derived from 2 diode solar cell model which is as given in equation in below link.

http://www.mathworks.de/de/help/physmod/elec/ref/solarcell.html or

I = Ip-Id1- Id2 - Ish

It is a perfectly working model, but does not include reverse characterstices of the cells.

My multiply a simple term to Ish term in equation {1 + a(1-Vj/Vbr)^-m} where the below variable depend on the type of solar cell and so user controlled.

a= fraction of shunt current involved in breakdow

m= Al valance current breakdown exponent

Vbr = jucntion of shunt current involved in breakdown.

Is there anyway i can add this eqatuion to pre existing equation of solar cell in matlab?

Thank you

Niti Panchal